Synthesis of seven-membered cyclic allenes, 1-zirconacyclohepta-2,3,6-trienes, from alkynes and 1-en-3-ynes

•Seven-membered metallacyclic allene compounds were prepared and structurally characterized.•These were synthesized by coupling between alkynes and 1-en-3-ynes.•Benzyne, an unstable alkyne, could be also employed for the reaction.•Molecular structures seem seven-membered allene, although contribution from other structure is possible.

Seven-membered metallacyclic allene compounds, 1-zirconacyclohepta-2,3,6-trienes, were synthesized by intermolecular coupling between alkynes and 1-en-3-ynes on a zirconium atom. X-ray diffraction studies and NMR spectroscopic observation indicated their seven-membered structures, although the contribution from 2-alkynyl-1-zirconacyclopent-4-ene might be considered. Benzyne, an unstable alkyne, also coupled with 1-en-3-ynes on zirconium and titanium.

Graphical abstractSeven-membered metallacyclic allene compounds were prepared by coupling between alkynes and 1-en-3-ynes. Benzyne, an unstable alkyne, could be also employed for the reaction.Figure optionsDownload full-size imageDownload as PowerPoint slide